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The Nyquist theoretical minimum bandwidth requirement. The ShannonHartley capacity theorem (and the Shannon limit) Government regulations. Technological limitations. Other system requirements (e.g satellite orbits) | : Modulation and Coding Tradeoff and Digital Communications Design Goals in designing a DCS Goals: Maximizing the transmission bit rate Minimizing probability of bit error Minimizing the required power Minimizing required system bandwidth Maximizing system utilization Minimize system complexity Error probability plane (example for coherent MPSK and MFSK) Bit error probability M-PSK M-FSK k=1,2 k=3 k=4 k=5 k=5 k=4 k=2 k=1 bandwidth-efficient power-efficient Design on the Error probability plane Bit error probability M-PSK M-FSK k=1,2 k=3 k=4 k=5 k=5 k=4 k=2 k=1 bandwidth-efficient power-efficient Selection of parameters - M in MP vs. MF - Eb/No for Pb requirement Limitations in designing a DCS Limitations: The Nyquist theoretical minimum bandwidth requirement The Shannon-Hartley capacity theorem (and the Shannon limit) Government regulations Technological limitations Other system requirements (e.g satellite orbits) Nyquist minimum bandwidth requirement The . | : Modulation and Coding Tradeoff and Digital Communications Design Goals in designing a DCS Goals: Maximizing the transmission bit rate Minimizing probability of bit error Minimizing the required power Minimizing required system bandwidth Maximizing system utilization Minimize system complexity Error probability plane (example for coherent MPSK and MFSK) Bit error probability M-PSK M-FSK k=1,2 k=3 k=4 k=5 k=5 k=4 k=2 k=1 bandwidth-efficient power-efficient Design on the Error probability plane Bit error probability M-PSK M-FSK k=1,2 k=3 k=4 k=5 k=5 k=4 k=2 k=1 bandwidth-efficient power-efficient Selection of parameters - M in MP vs. MF - Eb/No for Pb requirement Limitations in designing a DCS Limitations: The Nyquist theoretical minimum bandwidth requirement The Shannon-Hartley capacity theorem (and the Shannon limit) Government regulations Technological limitations Other system requirements (e.g satellite orbits) Nyquist minimum bandwidth requirement The theoretical minimum bandwidth needed for baseband transmission of Rs symbols per second is Rs/2 hertz. Shannon limit Channel capacity: The maximum data rate at which error-free communication over the channel is performed. Channel capacity of AWGV channel (Shannon-Hartley capacity theorem): Shannon limit The Shannon theorem puts a limit on the transmission data rate, not on the error probability: Theoretically possible to transmit information at any rate , with an arbitrary small error probability by using a sufficiently complicated coding scheme For an information rate , it is not possible to find a code that can achieve an arbitrary small error probability. Shannon limit C/W [bits/s/Hz] SNR [bits/s/Hz] Practical region Unattainable region Shannon limit There exists a limiting value of below which there can be no error-free communication at any information rate. By increasing the bandwidth alone, the capacity can not be increased to any desired value. Shannon limit
